This article is from the running Beginners' FAQ, by Ozzie Gontang with numerous contributions by others.
The main cause of injury in beginners is the mismatch between the rapid
development of the muscles and the slower development of the bones. In
particular, injuries commonly appear between 8-12 weeks after starting
training.
The most common symptoms are persistent calf-muscle soreness and discomfort
along the border of the shinbone (shin-splints). These symptoms will
usually disappear in time *if* you reduce the training load for a few weeks
- having more rest days and running less distance. If this does not work,
consider changing your running shoes to a more shock-absorbent pair,
running on softer surfaces (a good idea anyway) and possibly seeking
professional advice.
You may have a gait abnormality such as over or under pronation and
supination (how much your foot rolls in and out during its time on the
ground). Your legs may be different lengths. Sooner or later
these will cause problems, and you will have to discover what kinds of
motion control shoes work for you, or if you need orthotics. Hopefully this
will be in the far future, or never, but be aware of the problems.
The main rec.running faq has information on injuries and treatment, with a
large section on shin-splints.
 
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